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Chapter 5. Packet Processing > 5.7 Compression and Encryption - Pg. 237

5.7 Compression and Encryption 237 Since checksum is often changed in packet processing, some network processors contain an internal checksum functional unit to assist with maintaining the right checksums. In addition, traffic analysis, some management tasks (e.g., accounting) and other applications can be performed in the modification phase, although most of these operations are expected to be performed in the control path. Statistics collection, however, must be done in the fast path, at the modification phase, to accommodate the packet rate. 5.7 COMPRESSION AND ENCRYPTION Compression and encryption processing are optional phases in packet process- ing that are more typical to access network processors than to high-end net- work processors. The reason is that packets do not undergo any compression or encryption in the main trunks of the core and the metro networks, whereas these processes might happen at the edges of the network, at the access points. Usually, compression and encryption is executed by specific coprocessor, or in